Operators have adopted Wireless Local Area Network (WLAN) for branching data flow in a cellular data network in recent years. The cover range of WLAN has been spread out gradually from indoor to outdoor. WLAN has become a part and parcel of a commercial network system. For a commercial network available to the masses, controllable bandwidth allocation and management are basic requirements of the commercial network for operating. For example, in a Digital Subscriber Line (DSL) network, operators may provide different users with different networking rates, e.g., from 100 Kbps to 2 Mbps, according to networking service fees selected by the users. However, current WLAN technologies, products, and standards are mainly for an indoor and enterprise use, and performances of which (including workability, reliability and stability) have not met with the requirements of the commercial network available to the masses.
Particularly, existing channel access schemes in WLAN mainly include the following 1-3.
1. a contention-based channel access scheme as illustrated in FIG. 1: This scheme merely ensures user equipments accessing a network simultaneously to share uplink and downlink bandwidth resources of an air interface in a relatively fair way. Under the contention-based channel access scheme, mean channel efficiency drops rapidly along with an increasing number of user equipments accessing the network simultaneously, as illustrated in FIG. 2. Thus network resources are wasted greatly, a networking rate of a user is influenced with uncertain factors, and complaints from users occur frequently.
2. an enhanced contention-based channel access scheme: Four queues are maintained at the Access Point (AP) side for four different applications of voice, video, best effort, and background in this scheme. Bandwidth resources for the four different applications are controlled by scheduling the four queues. Specifically, different parameters in a link layer are adopted for data packets in the four queues to distinguish the priorities of the four different applications in contending for accessing a channel, where, data packets of voice have the highest priority, and priorities are degraded sequentially for data packets of video, best effort, and background. With the enhanced contention-based channel access scheme, only four predefined applications rather than users can be distinguished, and control with a finer granularity is not available.
3. an AP-controlled channel access scheme: This scheme defined in a preliminary standard of WLAN is similar to a channel resource allocation scheme in a cellular network. In this scheme, an AP has to poll all user equipments periodically to collect information of user equipments to be accessing a channel and scheduling the user equipments in a unified manner. This increases greatly a delay time of an internet session of a new device in requesting network resources. Particularly, when there are only a few user equipments accessing the network simultaneously, the channel efficiency of the AP-controlled channel access scheme is far below that of the contention-based channel access scheme. Moreover, a method for controlling a channel access based on the AP-controlled channel access scheme is too complicated, and the AP-controlled channel access scheme is not compatible with the existing contention-based channel access scheme and is not in use actually.